1. Field of the Invention
The present invention relates to a recording apparatus that ejects an ink to conduct recording and a liquid ejection head from which a liquid is ejected.
2. Description of the Related Art
A thermal system and a piezoelectric element system are representative of an ink jet recording system (Drop-On-Demand system) in which an ink is intermittently ejected from ejection orifices provided in a recording head according to recording information to apply the ink to a recording medium such as paper. In a recording apparatus using a recording head of such a system, the viscosity of an ink in the vicinity of the ejection orifices may be increased in some cases by evaporation of water in the ink in the vicinity of the ejection orifices and transfer of the ink attending thereon, whereby such a condition that the ink is not ejected from the ejection orifices or the amount of the ink ejected does not reach a desired value may be caused in some cases. In addition, when foggy ink mist that is ejected from the ejection orifices but does not reach a recording medium adheres around the ejection orifices in a sufficient amount, the ink mist adhered hinders the ejection of the ink to cause impact deviation of ink droplets.
When a recording apparatus using a recording head is intended to be applied to commercial recording of which high-speed recording is required, a recording head of a full-multi type in which ejection orifices are aligned corresponding to the overall width of a recording medium is often used. In the recording apparatus for commercial recording, continuous recording is desirably conducted over a long period of time for the purpose of completing recording on a great number of recording media in a short period of time. However, when such a suction ejection-recovery operation that ink is discharged from ejection orifices of a recording head is conducted during the recording for preventing the viscosity increase of the ink, the long-term continuous printing is hindered. In the recording head of the full-multi type, a great number of ejection orifices are arranged corresponding to the overall width of the recording medium, so that discharge of ink for recovery increases to greatly increase running cost. There is a demand for countermeasures for solving these problems to making up a recording head capable of conducting long-time continuous recording.
The countermeasure disclosed in Japanese Patent Application Laid-Open No. 2006-95857 is known as a countermeasure for the phenomenon of ink viscosity increase and the ink mist adhered to around the ejection orifices in the line printer. According to Japanese Patent Application Laid-Open No. 2006-95857, a recording head of a thermal system has an opening wider than the sectional area of each ejection orifice at an exterior surface of the recording head corresponding to the ejection orifices. A meniscus of an ink is retained at this opening. Adjoining openings are communicated with each other through a communicating portion. According to such a construction, floating ink mist is absorbed in the ink located at the opening even when the ink mist adheres to the opening, so that the ejection of the ink is not adversely affected by the ink mist. In addition, an ink in an opening located at a position corresponding to an ejection orifice from which no ink is ejected transfers to an opening located at a position corresponding to an ejection orifice from which the ink has been ejected through the communicating portion after the ejection of the ink. As a result, a fresh ink whose viscosity is not increased is supplied even to the opening corresponding to the ejection orifice from which no ink is ejected from a liquid chamber.
Even in the method disclosed in Japanese Patent Application Laid-Open No. 2006-95857, however, it is difficult to inhibit ejection failure caused by evaporation of water from the ink in a non-recording state where the ink is not ejected over a long period of time. When ejection of the ink is started after the non-recording state for the long period of time, lowering of recording quality and impact deviation may be caused in some cases because the viscosity of ink droplets just after the starting is increased. In addition, the ink is ejected from only particular ejection orifices according to recording information, so that ejection characteristics such as ejection velocity, ejected ink droplet quantity and ink refilling velocity may possibly vary between such particular ejection orifices and ejection orifices low in ejection frequency. This variation is considered to adversely affect the recording quality on a recording medium.